The aim of the present project was to further our understanding of the processes responsible for sensory transduction. Experiments were performed on the mechano-receptive hair cells and the photoreceptors in the marine mollusc Hermissenda crassicornis. Hair cells respond to mechanical stimulation with a depolarizing generation potential that is associated with an increase in membrane conductance. The features of the conductance change were reconstructed from the time course of the generator potential and the passive electrical properties of the cell membrane. It was found that the increase in conductance develops slowly and is roughly proportional to the energy delivered by the stimulus. The time course of the conductance change is similar to the output of a model involving a sequence of transformations. Hermissenda photoreceptors respond to illumination with triphasic generator potential; initial depolarization followed by hyperpolarization and finally a slow depolarization. The ion specificities for these potential changes are presently being investigated.